Rosenwach Tank Has Stayed In Business For 150 Years Doing Something That's Almost Obsolete

Six workers are swinging axes, hauling timber and throwing around an arsenal of power tools perched high above an old building on Harlem's 125th Street. With no scaffolding or supports, they're a rare sight. Even more unusual: they're building a wooden water tank.

This is the legendary construction team of Rosenwach Tank. They can put up a 10,000-gallon wooden water tank in less than half a day. You’ve seen their work.

The wooden tanks on top of buildings all over the city are a quirk of New York’s infrastructure. Wooden water tanks were vital in the early twentieth century, as the city grew skyward. They're the way many of the city's older buildings get their water supply, and have enough water stored to feed the sprinklers if there's a fire. They use wood because just three inches of wood insulate the tank as well as 24 inches of concrete would.

Rosenwach is the last company to make them in the city. It has been in business for almost 150 years doing something that's now almost obsolete.

The company is still around because while their market is disappearing, it’s disappearing very slowly.

“We’re in a dying business,” said Andrew Rosenwach, whose great-grandfather started the company. “When I was looking at joining, my father told me ‘If you join the family business and they stop putting tanks up, you’ll have enough business taking the tanks down,’” he said.

Companies in this position have a choice to make, say strategists. They can retreat into their niche and watch the clock wind down. Or, they can fight, by moving their business away from the obsolete.

Andrew Rosenwach has chosen to fight.

Essentially The Same Since 1865

As long as New York is still a city of old buildings, Rosenwach will be in business. While wood is still lighter than concrete, and a better insulator than steel, they’ll be putting wood tanks on newer buildings. But those days are numbered.

Founded in about 1865, Rosenwach Tank is an old school business. They make their own brass pipe: if they didn’t, it would cost $1200 a foot. They even mill their own wood in the company’s original Brooklyn workshop.

“It’s a unique job. Only three of us do it in a city of 10 million,” said Ken Lewis, who runs the Williamsburg workshop. Lewis has been at Rosenwach for 35 years, which, he acknowledged, was rare: “That’s just the way this company is,” he said.

“We survive on our own ingenuity and quality. That takes time,” said Andrew Rosenwach.

Surviving On Ingenuity, Timber And Steel

“We’re constantly reinventing ourselves,” said Andrew Rosenwach, taking us on a tour of a workshop in Queens. Rosenwach focused on using every facet of the their expertise Pointing to a massive bench made for a Staten Island park, he explained that they wanted to keep the wood shop busy through the year, so they spun-off a company that makes furniture and decks for parks and gardens.

With their expertise working on old buildings, they spun off another company that restores old facades. To keep the tank team busy during the winter, they fix sprinkler systems and service and build air conditioning cooling towers. Each wave of innovation meant serious investment.

“We survive on our own ingenuity and quality. That takes time,” said Rosenwach. “We’re not cutthroat,” but at the same time, “If you’re not up to speed with us, you’re not going to stay in business,” he added.

“Others move towards greater and greater diversification, like Colgate or Proctor & Gamble,” said Adner, author of ‘The Wide Lens: A New Strategy for Innovation,’ which explores why great products and businesses fall into obscurity.

“They [Rosenwach] are in a decaying market,” said Adner. “The real challenge will be shifting the core."

The problem is, wooden tanks still dominate Rosenwach’s business. The landscape furniture company, for example, keeps three or four men employed but it’s maybe 10 percent of the company’s value.

“[Our] future is dominated by the tank business,” he said. But that has to change as quickly as the city’s skyline.

On a recent Saturday, the Rosenwach crew were up early dismantling the old tank, and preparing the frame for a new, 10,000 gallon water tank. Here, foreman CJ Adonis is standing on the iron frame the tank will sit on.

The team does almost everything by hand, with an arsenal of tools. The process hasn’t changed a great deal since the company was founded around 1865.

“Water finds its level, and the difference between upstate New York, where the water comes from, and the city, where it ends up, is about six stories,” Ken Lewis explained. Getting water any higher than six stories needs a gravity-based system, like the tank, or a pump.

Back inside the Brooklyn workshop, Ken Lewis patches the base of a tank with epoxy. “It’s a unique job. only three of us do it in a city of 10 million,” he said. “Going down the street, I’ll see a tank, I’ll see the address, and I’ll realize I made that tank,” he said.

Owner Andrew Rosenwach has to constantly invest in heavy machinery. “Not only is it important to have the right machines, it’s important to have the right people,” he said.

The Rosenwach team fit the last planks, finishing the sides of the tank. The tank is secured with metal bands, which are repeatedly tightened until the tank is almost water-tight. Water leaks through the cracks in the tank as it's filled, until the wood expands, closing up all the gaps.